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iomap: move locking out of iomap_write_delalloc_release

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XFS (which currently is the only user of iomap_write_delalloc_release)
already holds invalidate_lock for most zeroing operations.  To be able
to avoid a deadlock it needs to stop taking the lock, but doing so
in iomap would leak XFS locking details into iomap.

To avoid this require the caller to hold invalidate_lock when calling
iomap_write_delalloc_release instead of taking it there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This commit is contained in:
Christoph Hellwig 2024-10-08 10:59:14 +02:00 committed by Carlos Maiolino
parent caf0ea451d
commit b784951662
2 changed files with 10 additions and 9 deletions
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17
fs/iomap/buffered-io.c
View File

@ -1211,12 +1211,13 @@ void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
loff_t scan_end_byte = min(i_size_read(inode), end_byte);
/*
* Lock the mapping to avoid races with page faults re-instantiating
* folios and dirtying them via ->page_mkwrite whilst we walk the
* cache and perform delalloc extent removal. Failing to do this can
* leave dirty pages with no space reservation in the cache.
* The caller must hold invalidate_lock to avoid races with page faults
* re-instantiating folios and dirtying them via ->page_mkwrite whilst
* we walk the cache and perform delalloc extent removal. Failing to do
* this can leave dirty pages with no space reservation in the cache.
*/
filemap_invalidate_lock(inode->i_mapping);
lockdep_assert_held_write(&inode->i_mapping->invalidate_lock);
while (start_byte < scan_end_byte) {
loff_t data_end;
@ -1233,7 +1234,7 @@ void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
if (start_byte == -ENXIO || start_byte == scan_end_byte)
break;
if (WARN_ON_ONCE(start_byte < 0))
goto out_unlock;
return;
WARN_ON_ONCE(start_byte < punch_start_byte);
WARN_ON_ONCE(start_byte > scan_end_byte);
@ -1244,7 +1245,7 @@ void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
data_end = mapping_seek_hole_data(inode->i_mapping, start_byte,
scan_end_byte, SEEK_HOLE);
if (WARN_ON_ONCE(data_end < 0))
goto out_unlock;
return;
/*
* If we race with post-direct I/O invalidation of the page cache,
@ -1266,8 +1267,6 @@ void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
if (punch_start_byte < end_byte)
punch(inode, punch_start_byte, end_byte - punch_start_byte,
iomap);
out_unlock:
filemap_invalidate_unlock(inode->i_mapping);
}
EXPORT_SYMBOL_GPL(iomap_write_delalloc_release);

2
fs/xfs/xfs_iomap.c
View File

@ -1239,8 +1239,10 @@ xfs_buffered_write_iomap_end(
if (start_byte >= end_byte)
return 0;
filemap_invalidate_lock(inode->i_mapping);
iomap_write_delalloc_release(inode, start_byte, end_byte, flags, iomap,
xfs_buffered_write_delalloc_punch);
filemap_invalidate_unlock(inode->i_mapping);
return 0;
}